Antibiotic eye drops and ointments
BMJ Group Medical Reference
Antibiotics are drugs that attack bacteria. If you have conjunctivitis, you put antibiotics into your eyes as drops or an ointment. Antibiotics can make your conjunctivitis clear up more quickly.
But the infection will probably go away on its own after a few days without any treatment. It might be worth waiting a few days to see if your symptoms start to clear up. If they don't, or they get worse, then you may need antibiotics.
Two common antibiotics used for conjunctivitis are:
You can buy chloramphenical eye drops and ointment from a pharmacy but you need a prescription for fusidic acid and moxifloxacin. Chloramphenicol eye drops can be used for adults and for children aged 2 and over.
If you use eye drops:
Wash your hands first. Be careful not to touch the tube/bottle tip or let it touch your eye
You need to gently pull down your lower eyelid to catch the drops
Usually all you need is one drop
Keep your eye closed for one or two minutes afterwards
Check with your doctor or pharmacist about how often you should use your eye drops
Continue your treatment for two days after your conjunctivitis has gone, or for as long as your doctor recommends
If you have trouble putting in eye drops, you can get a dispenser to help.
If you use an ointment:
Put it in your eyes the same way as eye drops. It will melt quickly, and if you blink it helps to spread it
Put it in either at night (and use eye drops during the day) or three to four times each day 
Ointment may blur your vision for around 20 minutes, but it can be easier to use than drops, especially for children.
If you wear contact lenses:
Ask your pharmacist or doctor about which treatment to use
Ask whether you need to leave your lenses out during treatment
Check whether your drops can be used with soft (hydrogel) contact lenses.  Some can't
If you wear disposable contact lenses, you should throw away the set of lenses and the lens case you were using. If you keep them you might get the same infection again
If you wear permanent lenses, ask your optician about what to do with them.
If your doctor thinks your conjunctivitis is caused by an infection with bacteria, antibiotics can help clear it up. One summary of the evidence (a systematic review) showed that you are more likely to be cured after 10 days if you use eye drops or ointment than if you don't.  Another systematic review found that more people who used moxifloxacin were cured than people who used a dummy treatment (a placebo). 
One study looked at people who definitely had bacterial conjunctivitis.  Some of the people used antibiotics and others used a placebo. The study found that after a week:
Lots of other studies have shown that antibiotics work well. The different types of antibiotic drops and ointments seem to work as well as each other. 
Antibiotics can cause some side effects, but they aren't usually serious. They can make your eyes sting for a short time.